1. Technical Field
Example embodiments relate to a comparator and/or an analog to digital converter having the same.
2. Description of the Related Art
Recently, a Charge Coupled Device (CCD) image sensor and a Complementary Metal Oxide Semiconductor (CMOS) image sensor are widely used as an image sensor. Typically, an image sensor includes an analog to digital converter that converts an analog signal (i.e., a pixel output voltage) output from a unit pixel into a digital signal. For example, the analog to digital converter may convert the analog signal to the digital signal by comparing the pixel output voltage with a ramp voltage, and by counting a clock signal until the ramp voltage is the same as the pixel output voltage. Therefore, the analog to digital converter includes a comparator for comparing the pixel output voltage with the ramp voltage. In case of a conventional comparator, however, a current consumed before a decision point of the conventional comparator is different from a current consumed after the decision point of the conventional comparator. As a result, a power voltage fluctuation may be caused by the conventional comparator in the analog to digital converter.